Benzanthrones and a process of preparing them



Patented Sept. 15, 1942 warren STATES ears were creme BENZANTHRONES AND A PROCESS 0F PREPARING THEM Heinrich Greune and Karl Schneider, Frankforton-the-Main-Hochst, Germany, assignors to General Aniline & Film Corporation, a corporation of Delaware No Drawing. Application April 22, 1939, Serial No. 269,412. In Germany June 18, 1938 8 Claims.

with, for instance, methylene acetone occurs like- Wise unequivocally, only in reversed order of Suecession. As final product of this reaction there is obtained the Bz-l-methylbenzanthrone and not the Bz-3-methylbenzanthrone. It results that the methyleneacetone is added at first at the double linkage to the anthrone and that this addition product forms, while water is split off and dehydrogenation occurs, the Bz-l-methylbenzannot been ascertained whether in this reaction the 10 throne:

on HC oo on 3 CH 2 a mo oo-om H2O 0-0113 m V H 1 H 110 o-cm ll H2o -11,

0 o 0 V o anthrone (or the anthanol) reacts at first with the aldehyde group or with the double linkage of the acroleine primarily formed from the glycerol, since in both cases as final product of the reaction the benzanthrone is obtained and an intermediate product has not been isolated.

The reaction described in German patent specification No. 490,187 of ii-anthrone with cinnamaldehyde occurs unequivocally, since by this reaction cinnamylideneanthrone is obtained as intermediate product and Bz-l-phenylbenzanthrone as final, product. In this case the aldehyde-group ofrthe oinnamaldehyde reacts at first with the anthrone, water being split ofi and the cinnamylideneanthrone being formed, and from this intermediate product there is formed by the dehydrogenating effect of the strong sulfuric acid the Bz-l-phenylbenzanthrone, so that the course of the reaction takes place according to the following scheme:

- The reaction described in German natent'specification No. 488,608 of anthrone or anthanol In view of these various possibilities of reaction of Q-anthrone or Q-anthanol with unsaturated aldehydes and ketones it was to be expected that by the reaction of alpha-beta-unsaturated alphahalogenaldehydes in each case benzanthrones halogen-substituted in Bz-Z-position would be obtained. 7

We have found that by condensing a 9-anthrone or 9-anthranol unsubstituted in at least one of its positions peri to the 10-position with an alpha-beta-unsaturated aldehyde of the following general formula wherein R means hydrogen or an alkyl radical, in the presence of sulfuric acid, benzanthrones are obtained, andpas a surprising fact the alphahalogen atom of the aldehyde is split off, probably in the form of hypochlorous acid which serves as a. suitable oxidizing agent for the dehydrogenation of the dihydrobenzanthrones formed as intermediate products. By using, for instance, alpha;chlorocrotonaldehyde there is obtained in the "course of a smooth reaction the Bz-3-methylbenzanthrone. The reaction probably occurs according to the following scheme:

by the saturated aldehydes of the following formula X halogen wherein R represents a member of the group consisting of hydrogen and alkyl and X represents a member of the group consisting of hydroxyl methoxyl and halogen, and the acetals of the aldehydes of both the formulae.

The benzanthrones thus obtained in most cases with a quantitative yield serve as intermediate products for the preparation of dyestufis.

According to the new process new benzanthrone derivatives are obtainable, for instance, Bz3- methylbenzanthrone compounds containing one or more substituents as, for instance, hydroxy, methoxy, methyl, halogen or carboxy. As compared with known processes for the preparation of benzanthrone derivatives the process of the present invention has the advantages that a better yield is obtained, that organic solvents and oxidizing agents are not necessary in the reaction and that the latter can be: carried out under mild conditions, for instance, at a low temperature of, for instance, between about 0 C. and room temperature and that products of good purity are obtained.

The following examples serve to illustrate the invention, but they are not intended to limit it thereto; the parts are by weight:

1. In the course of about half an hour 10.5 parts of alpha-chloro-crotonaldehyde are added, drop by drop, to an anthrone solution prepared by stirring for a prolonged time at room temperature 19.4 parts of anthrone and 300 parts of sulfuric acid of 80 per cent. strength. The solution assumes at once a red coloration and a test portion added to concentrated sulfuric acid shows an orange-yellow fluorescence. As soon as the reaction has fully set in streams of hydrogen chloride escape with vivid foaming. By vividly stirring for a prolonged time at room temperature the reaction is promoted. It may be brought to an end by stirring for about one hour at 70 C. The solution is poured on ice, while stirring, the crude product separates in the form of brown-yellow flakes. It is filtered with suction, washed until neutral and dried. The yield of the crude product is quantitative and after recrystallizing the product from methanol or ethanol it amounts to per cent. of the theory of the Bz-3-methylbenzanthrone melting. at 113 C. to 114 C. It dissolves in concentrated sulfuric acid to an orange-red solution having an intense yellow-red fluorescence.

It is not necessary that in this process solid anthrone is used, but the alpha-chloro-crotonaldehyde may also be added, drop by drop, to an anthrone solution prepared, for instance, by reduction of anthraquinone with a metal powder in sulfuric acid solution according to German patent specification No. 201,542, whereby the same result is obtained.

By using in the process of this example instead of alpha-chloro-crotonaldehyde the alphachloro-beta-ethylacroleine there is obtained the Bz-B-ethylbenzanthrone.

2. A mixture of 16 parts of alpha-bromo-crotonaldehyde (obtainable according to German patent specification No. 559,329) and parts of glacial acetic acid is added, drop by drop, within the course of 1 hour to a solution of 19.4 parts of anthrone in 300 parts of sulfuric acid of 80 per cent strength while cooling with ice. The solution assumes a dark red coloration whereas a vivid evolution of hydrogen bromide can be observed. The reaction is brought to an end and the product obtained with a quantita tive yield is worked up as indicated in Example 1. It is identical with the benzanthrone derivative obtained according to Example 1.

3. 14 parts of alpha-chloro-betal-methoxybutyraldehyde (obtainable by the addition of methanol to alpha-chloro-crontonaldehyde and boiling under a pressure of 10 mm mercury at 48 C. to 50 C.) are condensed with anthrone and worked up as described in Example 1. The benzanthrone derivative thus obtained with a quantitative yield is identical with that of Example 1.

4. 13 parts of alpha-chloro-beta-hydroxybutyraldehyde (obtainable by the addition of hypochlorous acid to the crontonaldehyde according to German patent specification No. 559,329) are condensed as indicated in Example 1 with 19.4 parts of anthrone and worked up as described in that example. The condensation product thus obtained with a quantitative yield is the Bz-3-methylbenzanthrone melting at 113 C. to 114 C. named in Example 1.

5. 13 parts of acroleindichloride (obtainable by the addition of chlorine to acrolein, cf. Moureau, Ann. Chim. (9), 15, page 158) are caused to react with anthrone as described in Example 1. From the crude product there is removed a small quantity of anthraquinone by extracting with a hot alkaline hydrosulfite solution. The product obtained with a nearly quantitative yield is unsubstituted benzanthrone free from chlorine and melts at 172 c.

6. 22.8 parts of 2-chIoro-9-anthrone are treated in 300 parts of sulfuric acid of about 80 per cent. strength, as described in Example 1, with 10.5 parts of alpha-chloro-crotonaldehyde. There is obtained .the 6-chloro-Bz-3-methylbenzanthrone recrystallizing from toluene in the form of yellow leaflets and melting at 180 C. to 182 C. It dissolves in concentrated sulfuric acid to an orange-red solution having a yellow-red fluorescence. The crude yield is quantitative. 7

Analysis:

Foundi :76.68 and 76.76 H: 3.66 3.71 Cl=13.71 13.80 Calculated: C=77.56 H: 3.98 01: 12.74

7. By using for the condensation according to Example 1 instead of anthron 21 parts of l-hydroXy-9-anthrone, a hydroxy-Bz-3-methylbenzanthrone in which the hydroxy-group probably stands in -position is obtained with a quantitative yield and melts at 183.5 C. to 184.5 C. It may be recrystallized from acetone in the form of brown-yellow coarse needles. It dissolves in concentrated sulfuric acid to a yellow solution having a yellow-green fluorescence.

Analysis:

Found: C=82.74

H: 4.67 Calculated: 0:83.05 H: 4.65

8. By substituting for the anthrone used in Example 1 25.4 parts of 3.4-dimethoxy-9-anthrone there is obtained with a quantitative yield, after saponification of the reaction product, the 7.8-dihydroxy-Bz-3-methylbenzanthrone melting at 218 C. to 220 C., which recrystallizes from methanol in the form of brown-yellow leaflets. The new benzanthrone derivative dissolves in dilute alkali and in concentrated sulfuric acid to a red solution.

9. By using for the reaction according to Example 1 instead of anthrone 22.4 parts of 4- methoxy-Q-anthrone the 8-methoxy bz.-3-methlybenzanthrone is obtained with a quantitative yield which crystallizes from glacial acetic acid in the form of brown-yellow needles and melts at 120 C. to 122 C. It dissolves in concentrated sulfuric acid to a blue-red solution having a reddish fluorescence.

10. By using for the reaction according to Example 1 instead of the anthrone 22.5 parts of 1-hydroxy-4-methyl-9-anthrone, the 5-hydr0xy- 8-methyl-Bz-3-methylbenzanthrone is obtained with a quantitative yield which crystallizes from acetone in the form of yellow needles and melts at 198 C. to 200 C. It dissolves in concentrated sulfuric acid to a yellow solution having a green fluorescence.

11. By replacing in Example 1 the anthrone by 22.7 parts of 1.8-dihydroxy-9-anthrone, the 4.5-dihydroxy-bz-3-methylbenzanthrone is obtained with a quantitative yield. It crystallizes from glacial acetic acid in the form of red needles and melts at 248 C. It dissolves in concentrated sulfuric to an orange-red solution having a yellow-red fluorescence.

12. By using for the reaction according to Example 1 instead of the anthrone 22.7 parts of 1.5- dihydroxy-9-anthrone there is obtained a 4.8- dihydroxy-Bz-3-methylbenzanthrone with a quantitative yield which crystallizes from glacial acetic acid in the form of yellow-brown needles and melts at 262 C. to 263 C. It dissolves in concentrated sulfuric acid to a yellow-red solution having a green fluorescence and in dilute alkali to an orange-yellow solution.

13. 10.5 parts of alphaechloro-crotonaldehyde are added, drop by drop,'at room temperature to a solution of 23.8 parts of 9-anthrone-2-carboxylic acid (obtainable by reduction of benzophenon-2,4'-dica1'-boxylic acid and subsequent ring closure according to Limpricht, Annalen 309, 115

"and. 121, lCf. also German patent specification No.

254,023) in 600 parts of sulfuric acid of 90 per cent. strength. The reaction is brought to an end by stirring for a prolonged time first at room temperature and finally at a raised temperature as described in Example 1.v The Bz-3-methylbenzanthrone-fi-carboxylic acid obtained with a quantitativeyield is purified by dissolving it in dilute ammonia, boiling with animal charcoal and precipitating by means of acid. Recrystallized from chlorobenzene or nitrobenzene it forms a yellow powder of coarse small crystals, sintering at 286 C. and melting at 288 C. to 289 C. In dilute sodium carbonate solution the acid dissolves -readily to a yellow solution and in concentrated sulfuric acid to a light yellow solution having a green-yellow fluorescence.

14. 18.2 parts of alpha-chloro-beta-methoxybutyraldehyde-dimethylacetal which is obtainable by introducing chlorine into a mixture of crotonaldehyde and methanol and boils under a pressure of 10 mm. mercury at 48 C. to 50 C., are condensed with anthrone and worked up as described in Example 1. The benzanthrone derivative obtained is identical with that obtained according to Example 1. The yield of the pure recrystallized lproduct amounts to per cent. of the theoretical.

We claim:

1. The process which comprises adding, while stirring, to a solution in sulfuric acid of a compound of the group consisting of Q-anthrones and Q-anthranoles which are unsubstituted in at least one of their positions peri to the 10-position a compound of the group consisting of those of the general formulae halogen R-C H=C-C H and halogen X I and the aldehydeoacetals thereof, wherein R represents a member of the group consisting of hydrogen and alkyl and X represents a member of the group consisting of hydroxyl, methoxyl and halogen,

2. The process which comprises adding, fwhile stirring, to a solution in sulfuric acid of a compound of the group consisting of Q-anthrones and Q-anhranoles which are unsubstituted in at least one of their positions peri to the 10-position -'a compound of the general formula halogen wherein R represents a member of the group consisting of hydrogen and alkyl.

3. The process which .comprises adding, while stirring, at :a. temperature between 0 C. and room temperature to a solution in sulfuric acid of a compound of the group consisting of 9-anthrones and Q-anthranoles which are unsubstituted in at least one of their positions per-i to the ln-position a compound of the general formula halogen 5. The process which comprises drop ing, while stirring, at about room temperature alpha-chlorocroton-aldehyde into a solution of 9-anthrone in sulfuric acid of 80 per cent. strength.

6. The process which comprises dropping, while stirring, at about room temperature alpha-chloro-scroton-aldehyde into a solution of 2-chloro-9- anthrone in sulfuric acid of 80 per cent. strength.

7. The process which comprises dropping, while stirring, at about room temperature alpha-chloro-acroton-aldehyde into a solution of 9-anthrone- 2-lcarboxyli c acid in sulfuric acid of 80 percent. strength.

8. Bz-3-methyl-6-chlorobenzanthrone melting at 180 C. to 182 C. and dissolving in concentrated sulfuric acid to an orange-red solution having a yellow-red fluorescence.

HEINRICH GREUNE. KARL SCHNEIDER. 

